{"id":"CVE-2021-21419","aliases":["GHSA-9p9m-jm8w-94p2","PYSEC-2021-12"],"title":"Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet","summary":"Improper Handling of Highly Compressed Data (Data Amplification) and Memory Allocation with Excessive Size Value in eventlet","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","vendor":"eventlet","product":"eventlet","ecosystem":"pip","affected":["eventlet >= 0.10, < 0.31.0"],"patched":["eventlet 0.31.0"],"published":"2021-05-07","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-9p9m-jm8w-94p2","references":[{"url":"https://github.com/eventlet/eventlet/security/advisories/GHSA-9p9m-jm8w-94p2"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21419"},{"url":"https://github.com/eventlet/eventlet/commit/1412f5e4125b4313f815778a1acb4d3336efcd07"},{"url":"https://github.com/eventlet/eventlet"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/eventlet/PYSEC-2021-12.yaml"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2WJFSBPLCNSZNHYQC4QDRDFRTEZRMD2L"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R5JZP4LZOSP7CUAM3GIRW6PIAWKH5VGB"}],"tags":["osv","pip"],"epss":0.01807,"epssPercentile":0.77658,"ingestedAt":"2026-07-08T18:25:48.054Z","slug":"CVE-2021-21419","body":"## Overview\n\n### Impact\nA websocket peer may exhaust memory on Eventlet side by sending very large websocket frames. Malicious peer may exhaust memory on Eventlet side by sending highly compressed data frame.\n\n### Patches\nVersion 0.31.0 restricts websocket frame to reasonable limits.\n\n### Workarounds\nRestricting memory usage via OS limits would help against overall machine exhaustion. No workaround to protect Eventlet process.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [eventlet](https://github.com/eventlet/eventlet/issues)\n* Contact current maintainers. At 2021-03: temotor@gmail.com or https://t.me/temotor\n\n## Affected packages\n\n- `eventlet >= 0.10, < 0.31.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `eventlet 0.31.0`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":29.2,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}